Progress on human rights in Tunisia following last year's Arab spring revolution is being reversed by the current government, Amnesty International has warned, as the country marks the first anniversary of free and fair democratic elections.

Reforms that followed the overthrow of President Zein al-Abidine Ben Ali in January 2011 – including the release of political prisoners, new laws on press freedom and associations — have not been maintained, it says. Last October's elections were widely praised as representing a model transition to democracy.

But in the latest in a series of critiques by international human rights watchdogs, Amnesty says that recent months have seen new restrictions on freedom of expression targetting journalists, artists, critics of the government, writers and bloggers.

"Protesters, who have continued to take to the streets in different parts of Tunisia to express their dissatisfaction with the slow pace of reform, have been met with unnecessary and excessive force," Amnesty said, adding that that it has received reports of torture and other ill-treatment, "many of them from protesters who alleged they were beaten during demonstrations, during arrest or in detention centres".

A state of emergency in place since the uprising has been repeatedly renewed, most recently until the end of this month. The Tunisian authorities have also appeared "unable or unwilling" to protect individuals from attacks by those believed to be affiliated with Salafist groups.

Last week, Human Rights Watch said it had documented a series of attacks by radical religious groups against political activists, which the authorities had failed to investigate. HRW also expressed concern that a draft law prohibiting Ben Ali-era government officials from seeking office was too restrictive and would not advance "inclusive democracy".

Tunisian journalists also went on strike, accusing the government of seeking to impose new controls. Investigators from the UN and African Union also recently noted human rights violations, including attacks against journalists, artists and activists, torture, threats by conservative Islamic groups and the excessive use of force against demonstrators by police.

Tunisia was the first and most peaceful of the uprisings of the Arab spring, sending shockwaves across the Middle East and north Africa when Ben Ali, who had ruled the country since 1987, was forced from power and fled into exile in Saudi Arabia.

It was also the first Arab country to see the rise to power of an Islamist party, En-Nahda, which was banned before the revolution. It now rules in coalition with the Congress for the Republic party of President Moncef Marzouki.

Beji Caid Essebsi, Tunisia's first prime minister after the revolution, has called the death of one of his party's senior officials during violence last week a "political assassination" and referred to the "lynching" of Lotfi Naguedh.